Differential cross section and analysing power of the pp→{pp}sπ0 reaction at 353 MeV

The differential cross section dσ/dΩ and analysing power Ay of the p→p→{pp}sπ0 reaction have been measured at COSY-ANKE at 353 MeV. The final proton pair was detected at very low excitation energy, leading to an S-wave diproton, denoted here as {pp}s. The angular dependence of both dσ/dΩ and Ay can be described in terms of s- and d-wave pion production. By using phase information from elastic pp scattering, unique solutions are derived for the corresponding amplitudes only as a result of the combined analysis of both experimental observables. The large d-wave term thus obtained is important for the tests of the current state-of-the-art chiral perturbation theory approach. The amplitudes will also help towards determining the isospin dependence of pion production in nucleon-nucleon collisions with diproton formation.